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mirror of https://github.com/cwinfo/yggdrasil-go.git synced 2024-12-23 04:05:39 +00:00

Clean up util package

This commit is contained in:
Neil Alexander 2021-06-05 20:55:08 +01:00
parent e67ee9232d
commit cb536a7322
2 changed files with 0 additions and 122 deletions

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@ -5,35 +5,9 @@ package util
// These are misc. utility functions that didn't really fit anywhere else
import (
"runtime"
"strconv"
"strings"
"time"
)
// Yield just executes runtime.Gosched(), and is included so we don't need to explicitly import runtime elsewhere.
func Yield() {
runtime.Gosched()
}
// LockThread executes runtime.LockOSThread(), and is included so we don't need to explicitly import runtime elsewhere.
func LockThread() {
runtime.LockOSThread()
}
// UnlockThread executes runtime.UnlockOSThread(), and is included so we don't need to explicitly import runtime elsewhere.
func UnlockThread() {
runtime.UnlockOSThread()
}
// ResizeBytes returns a slice of the specified length. If the provided slice has sufficient capacity, it will be resized and returned rather than allocating a new slice.
func ResizeBytes(bs []byte, length int) []byte {
if cap(bs) >= length {
return bs[:length]
}
return make([]byte, length)
}
// TimerStop stops a timer and makes sure the channel is drained, returns true if the timer was stopped before firing.
func TimerStop(t *time.Timer) bool {
stopped := t.Stop()
@ -61,70 +35,3 @@ func FuncTimeout(timeout time.Duration, f func()) bool {
return false
}
}
// Difference loops over two strings and returns the elements of A which do not appear in B.
// This is somewhat useful when needing to determine which elements of a configuration file have changed.
func Difference(a, b []string) []string {
ab := []string{}
mb := map[string]bool{}
for _, x := range b {
mb[x] = true
}
for _, x := range a {
if !mb[x] {
ab = append(ab, x)
}
}
return ab
}
// DecodeCoordString decodes a string representing coordinates in [1 2 3] format
// and returns a []uint64.
func DecodeCoordString(in string) (out []uint64) {
s := strings.Trim(in, "[]")
t := strings.Split(s, " ")
for _, a := range t {
if u, err := strconv.ParseUint(a, 0, 64); err == nil {
out = append(out, u)
}
}
return out
}
// GetFlowKey takes an IP packet as an argument and returns some information about the traffic flow.
// For IPv4 packets, this is derived from the source and destination protocol and port numbers.
// For IPv6 packets, this is derived from the FlowLabel field of the packet if this was set, otherwise it's handled like IPv4.
// The FlowKey is then used internally by Yggdrasil for congestion control.
func GetFlowKey(bs []byte) uint64 {
// Work out the flowkey - this is used to determine which switch queue
// traffic will be pushed to in the event of congestion
var flowkey uint64
// Get the IP protocol version from the packet
switch bs[0] & 0xf0 {
case 0x40: // IPv4 packet
ihl := (bs[0] & 0x0f) * 4 // whole IPv4 header length (min 20)
// 8 is minimum UDP packet length
if ihl >= 20 && len(bs)-int(ihl) >= 8 {
switch bs[9] /* protocol */ {
case 0x06 /* TCP */, 0x11 /* UDP */, 0x84 /* SCTP */ :
flowkey = uint64(bs[9])<<32 /* proto */ |
uint64(bs[ihl+0])<<24 | uint64(bs[ihl+1])<<16 /* sport */ |
uint64(bs[ihl+2])<<8 | uint64(bs[ihl+3]) /* dport */
}
}
case 0x60: // IPv6 packet
// Check if the flowlabel was specified in the packet header
flowkey = uint64(bs[1]&0x0f)<<16 | uint64(bs[2])<<8 | uint64(bs[3])
// If the flowlabel isn't present, make protokey from proto | sport | dport
// if the packet meets minimum UDP packet length
if flowkey == 0 && len(bs) >= 48 {
switch bs[9] /* protocol */ {
case 0x06 /* TCP */, 0x11 /* UDP */, 0x84 /* SCTP */ :
flowkey = uint64(bs[6])<<32 /* proto */ |
uint64(bs[40])<<24 | uint64(bs[41])<<16 /* sport */ |
uint64(bs[42])<<8 | uint64(bs[43]) /* dport */
}
}
}
return flowkey
}

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@ -1,29 +0,0 @@
package util
import "runtime"
var workerPool chan func()
func init() {
maxProcs := runtime.GOMAXPROCS(0)
if maxProcs < 1 {
maxProcs = 1
}
workerPool = make(chan func(), maxProcs)
for idx := 0; idx < maxProcs; idx++ {
go func() {
for f := range workerPool {
f()
}
}()
}
}
// WorkerGo submits a job to a pool of GOMAXPROCS worker goroutines.
// This is meant for short non-blocking functions f() where you could just go f(),
// but you want some kind of backpressure to prevent spawning endless goroutines.
// WorkerGo returns as soon as the function is queued to run, not when it finishes.
// In Yggdrasil, these workers are used for certain cryptographic operations.
func WorkerGo(f func()) {
workerPool <- f
}